A voice recognition apparatus has been incorporated into a car navigation system as voice recognition technology progresses. Thereby, even during driving of a vehicle, the user can search for a desired one of tens of thousands of facilities existing in the whole country safely while pinpointing the desired facility by simply uttering, for example, its address. Such a conventional voice recognition apparatus can also provide a voice guidance, such as a guidance to a destination, in response to a system operation performed by the user, and enables conversations in both directions.
As a voice recognition apparatus as mentioned above, a related art voice recognition apparatus which determines how much the user gets used to performing an operation from the number of times that a guidance has been provided to the user or the reaction time of the user, and increases the speed at which to provide a voice guidance and simplifies information about the guidance when the degree to which the user gets used to performing the system operation is higher than a predetermined level is known (for example, refer to patent reference 1).
Furthermore, a related art voice recognition apparatus which determines, as a level of the driving operation load on the user, vehicle speed information, handle steering angle information, and whether the vehicle is forwarding or reversing, and changes an automated voice guidance to the user on the basis of the determined driving operation load level is also known (for example, refer to patent reference 2).    [Patent reference 1] JP,2001-22370,A    [Patent reference 2] JP,2004-348657,A
A problem with the technology disclosed by above-mentioned patent reference 1 is that the voice guidance can be automatically changed according to the degree to which the user gets used to performing the system operation, while if the user does not understand recognized words, any voice guidance suitable for the user cannot be provided.
Furthermore, a problem with the technology disclosed by above-mentioned patent reference 2 is that the method of automatically answering by voice can be changed on the basis of the user's driving operation load level, while in case in which the user cannot understand words which the user can utter using the technology because the user cannot catch the guidance (e.g., because he or she did not hear it), any voice guidance suitable for the user cannot be provided because the degree of understanding of recognized words is not determined for every user.
The present invention is made in order to solve the above-mentioned problems, and it is therefore a object of the present invention to provide a vehicle-mounted voice recognition apparatus which, even when a user cannot understand words which the user can utter because the user could not catch the guidance or did not hear the guidance, makes it easy for the user to catch the description of the guidance or enables the user to catch the description of the guidance by changing the description of the guidance so that the user can grasp words which the user can utter.